百度：Instructions for Form W-8BEN-E
http://www.wjxfpf.com/2015/10/614104.html
https://developer.apple.com/library/ios/documentation/LanguagesUtilities/Conceptual/iTunesConnect_Guide/Chapters/ManagingContractsandBanking.html#//apple_ref/doc/uid/TP40011225-CH21
Providing U.S. Tax Information
Important: The iTunes Connect tax pages offer different information depending on the choices you make the first time you open the pages. If you make the wrong choices the first time through the pages, you won’t have an opportunity to change those choices. To avoid problems in the future, be careful to enter accurate information.
